1,2-Thiazoles by Ring Transformation of 2H-Thiopyran-2-thiones

Article abstract of DOI:10.1007/BF01045306

Aminolyses of 4-dialkylamino-2-methylthiothiopyranes halides with ammonia leads to 4-amino-2-dialkylaminothiopyranylium halides.On treatment with alkali these products are hydrolyzed to N,N-dialkyl-3-amino-2,4-hexadienthioamides, which react with peroxide under oxidative cyclization to 5-dialkylamino-1,2-thiazoles.In order to determine the structures of the unsaturated thioamides and isothiazoles 13C-NMR-spectroscopic analysis and a single crystal X-ray structure analysis of 5-dimethylamino-3-(2-methyl-1-propenyl)-1,2-thiazole (6a) at 100 K were carried out.C9H14N2S, M_r = 182.28, monoclinic, P 2₁/a, a = 11.622(2), b = 6.303(1), c = 13.678(2), β = 104.49(3) deg, V = 970.1(3) Angstroem³, Z = 4, d_x = 1.248 g/cm³, μ = 27.0 mm^-1, R = 4.93percent, R_w = 4.84percent (1672 observations, 157 parameters).Keywords: Oxidative cyclization; 1,2-Thiazoles; 13C-NMR-data; X-Ray analysis.